What you get is what they have? Detectability of intestinal parasites in reptiles using faeces

Detection of Trypanosoma cruzi DNA in lizards: Using non-lethal sampling techniques in a sylvatic species with zoonotic reservoir potential in Chile

Several reptile species have been described as hosts of Trypanosoma cruzi, the causative agent of Chagas disease, and therefore, they have become vertebrates of epidemiological interest. In recent decades, there has been a growing interest in animal welfare, especially in populations with small numbers where lethal sampling could have catastrophic consequences, and non-lethal methodologies have been developed for detecting zoonotic parasites. In this study, we compared three non-lethal sampling methodologies for detecting T. cruzi DNA in 21 captured specimens of the native lizard Liolaemus monticola, collected from the semiarid Mediterranean ecosystem of Chile. Specimens were subjected to xenodiagnosis (XD), tail clipping, and living syringe sampling procedures to evaluate whether lizards could serve as sentinel species for T. cruzi in endemic regions. To detect the protozoan, real-time PCR (qPCR) was performed on the DNA extracted from the samples (intestinal contents, tail tissues, and blood from living syringes). Trypanosoma cruzi DNA was detected in 12 of 21 lizards, considering all three methodologies. By XD, 12 specimens showed infection (57.1 %), and both living syringe and tail sampling methodologies detected only one infected lizard (4.8 %). Therefore, T. cruzi can be detected in lizards by qPCR using the three methodologies but XD is by far the most effective non-lethal detection methodology. The use of tail and living syringe methodologies showed a large underestimation; however, they might be options for monitoring the presence of T. cruzi in lizard populations when large sample sizes are available.

A Phylogenetic Assessment of Nematodes (Oxyuroidea: Pharyngodonidae) Infecting Moroccan Lizards

Molecular tools can be used to estimate the phylogeny of species and to identify cryptic diversity, but their use for parasites has lagged behind that of free-ranging organisms. As an example, in North Africa there is minimal molecular data available for helminth parasites of lizards. In this work we used two molecular markers (the nuclear 18S rRNA and the mitochondrial Cytochrome c Oxidase subunit 1) to investigate the diversity of nematodes of the family Pharyngodonidae parasitizing three genera of lizards from Morocco (Chalcides, Quedenfeldtia and Tarentola) and to explore their co-evolutionary history. Morphological assessments indicated that members of three genera were present: Spauligodon, Thelandros, and Parapharyngodon. Phylogenetic analysis of 18S rRNA sequences indicated the monophyly of the genus Spauligodon, and that some lineages could be distinguished, including Spauligodon auziensis from the host species Tarentola mauritanica, and another unnamed lineage from hosts of the genus Chalcides. However, with this slow-evolving marker some species could not be distinguished. The genus Thelandros was not monophyletic, although relationships were not strongly supported. Analysis of the faster evolving mitochondrial marker clearly separated various species of Spauligodon, as well as distinct unnamed lineages identified in the host genus Chalcides and the host Quedenfeldtia moerens.

Automatic identification of intestinal parasites in reptiles using microscopic stool images and convolutional neural networks

Captive environments trigger the propagation and multiplication of parasites among different reptile species, thus weakening their immune response and causing infections and diseases. Technological advances of convolutional neural networks have opened a new field for detecting and classifying diseases which have shown great potential to overcome the shortcomings of manual detection performed by experts. Therefore, we propose an approach to identify six captive reptiles parasitic agents (Ophionyssus natricis, Blastocystis sp, Oxiurdo egg, Rhytidoides similis, Strongyloides, Taenia) or the absence of such parasites from a microscope stool images dataset. Towards this end, we first use an image segmentation stage to detect the parasite within the image, which combines the Contrast Limited Adaptive Histogram Equalization (CLAHE) technique, the OTSU binarization method, and morphological operations. Then, we carry out a classification stage through MobileNet CNN under a transfer learning scheme. This method was validated on a stool image dataset containing 3616 images data samples and 26 videos from the six parasites mentioned above. The results obtained indicate that our transfer learning-based approach can learn a helpful representation from the dataset. We obtained an average accuracy of 94.26% across the seven classes (i.e., six parasitic agents and the absence of parasites), which statistically outperformed, at a 95% confidence level, a custom CNN trained from scratch.

New host and locality records of helminths' infection of seven lizards from Morocco

Morocco has a great diversity of reptiles; more than 26% of the herpetofauna species are considered to be endemic. Nevertheless, there is little information available on helminth parasites of Moroccan lizards. The purpose of this article is to establish a helminth list using non-invasive methods for natural populations of seven lizard species: Acanthodactylus maculatus, Chalcides mionecton, Chalcides montanus, Chalcides polylepis, Quedenfeldtia moerens, Quedenfeldtia trachyblepharus, and Tarentola mauritanica. For each species, prevalence and intensity of infection were given as well as their relationship to some determinant parameters (sex, age class, size, altitude, and seasons). Four species of nematodes, Parapharyngodon micipsae, Pharyngodon mamillatus, Spauligodon auziensis, Thelandros alatus, and unassigned Spauligodon were found. Mean helminth intensity for the seven lizard species was 7.3 ± 16.2 SD (range = 1-92 in infected lizards), with total infection prevalence of 5.6%. Mixed infections were observed in Chalcides montanus and Chalcides polylepis co-infected by Pharyngodon mamillatus and Spauligodon sp. Furthermore, the intensity of infection by nematodes were significantly different among the seven studied species. The nematode infection in Chalcides mionecton were related to sex, host size, and altitude; in Chalcides polylepis to the host age; in Quedenfeldtia trachyblepharus to elevation, age, and host size; and in Tarentola Mauritanica to age, body size, seasons, and altitude. In conclusion, our study provides data about nine new host and locality records and the effect of some determinant factors on host parasitism.

Coproparasitologic survey of gastrointestinal parasites in a captive leopard geckos collection (Eublepharis macularius)

An increase in exotic animal imports has been noticed in the last decades worldwide. In this scenario, reptiles represent a quite popular group of interest as exotic pets. However, they can harbor pathogens that under inadequate captivity conditions can lead to disease expression and sometimes death. This study performed coprological analysis to investigate gastrointestinal parasites in a private collection of leopard geckos (E. macularius) relating the results with husbandry practices. Twenty-three geckos of 1 to 5 years, weighing 30-65 g, of both sexes were used. Freshly voided fecal samples were collected and centrifugal fecal float technique was performed using Sheather's sugar solution. 65,21% animals were positive for gastrointestinal parasites. No animal presented any clinical signs but previous loss was reported in the colony. Among affected animals, 93,3% presented oxyurid eggs, 33,33% Strongyloidea eggs and 26,66% presented mite eggs. Four animals were infected with both nematodes. The groups found are commonly reported in captive reptiles and, due to their direct life cycle, reinfection is common in captive animals. The husbandry practices proved to be insufficient and preventive measures such as quarantine were not adopted by the owner, which can compromise not only the reptiles health but also people who deal with them.

GEOGRAPHICAL VARIATION OF ENTEROPARASITISM IN THE SOUTHERN SEA LION OTARIA FLAVESCENS (SHAW, 1800) OFF THE COAST OF CHILE AS EVIDENCED WITH COPROLOGICAL TESTS: IMPLICATONS FOR ZOONOTIC RISKS

The scarce information on the helminth fauna in otariids from the Southeastern Pacific comes mainly from stranded individuals or killed for that purpose. In this study, we compared the abundance and composition of enteroparasitic assemblages of Otaria flavescens using coprological techniques. Three sampling localities from north to south spanning 2,200 km off the Chilean coast were considered (Iquique, Viña del Mar, and Talcahuano). In all, 60 fecal samples were collected, and eggs belonging to 5 taxa were found in 91.6% of the samples. They were the anisakid nematodes Contracaecum and Pseudoterranova, the cestode Adenocephalus (syn. Diphyllobothrium), the trematode Ogmogaster, and the acanthocephalan Corynosoma. Samples from southern Chile (Talcahuano) showed the highest prevalence. Adenocephalus eggs had the highest prevalence and abundance in Iquique and Talcahuano, whereas Ogmogaster was the less prevalent and abundant in all sampling localities. Corynosoma eggs had similar prevalence and abundance among sampling localities, and Pseudoterranova eggs were absent in Iquique and with median prevalence values in Viña del Mar and Talcahuano. Thus, the composition of parasite egg assemblages was different between sampling localities. These differences between sampling localities may help to explain differential records of some zoonotic parasitoses such as pseudoterranovosis and diphyllobothriosis in Peru and Chile, where consumption of raw or marinated fish (ceviche) is common. For example, the lower diversity of parasite egg assemblages in the northern Chilean coast may be due to the absence or lower abundance of first intermediate/paratenic hosts of Pseudoterranova.

Determinants of prevalence and co-infestation by ecto- and endoparasites in the Atlas day gecko, Quedenfeldtia trachyblepharus, an endemic species of Morocco

The present work was undertaken to investigate the occurrence of ectoparasites (mites and ticks) and endoparasites (haemogregarines and helminths) in the Atlas day gecko, Quedenfeldtia trachyblepharus (Boettger, 1874), a high-altitude Moroccan endemic lizard. The study examinated also the effect of some host parameters (age, sex, size, body condition), in addition to the season and altitude on the prevalence and intensity of parasite infestations. The study was conducted in three localities from May to September 2019. The results indicated that 35% of juvenile geckos were found to be parasited by one type of parasite. Contrarily, up to three types of parasites were detected in the adults. The prevalence of mite infestations was 48.02%, with a mean intensity of 11.80 ± 15.69. The patterns of mite infestations was found to be mainly related to the altitude, while the prevalence and intensity of infestations were linked to the host size, and to the sex and season, respectively. Larvae and nymphs of Ixodes ricinus (Linnaeus, 1758) were the only life stages infesting geckos, with a prevalence and mean intensity of infestations of 4.41% and 2.2 ± 1.48, respectively. The tick infestations observed were mainly related to the season. The prevalence and intensity of haemogregarine infections were, respectively, 7.92% and 0.24 ± 0.15. The altitude was found to be the only factor associated with this infection. This study also revealed the presence of one helminth genus, Spauligodon sp., with a prevalence and mean intensity of 12.33% and 1.46 ± 0.88, respectively. Spauligodon infestations was significantly associated with age, host size and altitude. This finding represents the first citation of this parasite in Quedenfeldtia genus. Our study indicated that there was no significant relationship between parasite load and geckos body condition, which suggested a stable interaction between the gecko and its parasites. However, it showed a difference of infection between the localities, which could be in relation with habitat conditions.

Altitudinal Effects on Innate Immune Response of a Subterranean Rodent

Immune defense is costly to maintain and deploy, and the optimal investment into immune defense depends on risk of infection. Altitude is a natural environmental factor that is predicted to affect parasite abundance, with lower parasite abundance predicted at higher altitudes due to stronger environmental stressors, which reduce parasite transmission. Using high and low altitude populations of the Turkish blind mole-rat (TBMR) Nannospalax xanthodon, we tested for effects of altitude on constitutive innate immune defense. Field studies were performed with 32 wild animals in 2017 and 2018 from two low- and one high-altitude localities in the Central Taurus Mountains, at respective altitudes of 1010 m, 1115 m, and 2900 m above sea level. We first compared innate standing immune defense as measured by the bacteria-killing ability of blood serum. We then measured corticosterone stress hormone levels, as stressful conditions may affect immune response. Finally, we compared prevalence and intensity of gastrointestinal parasites of field-captured TBMR. We found that the bacteria-killing ability of serum is greater in the mole-rat samples from high altitude. There was no significant difference in stress (corticosterone) levels between altitude categories. Coccidian prevalence and abundance were significantly higher in 2017 than 2018 samples, but there was no significant difference in prevalence, abundance, or intensity between altitudes, or between sexes. Small sample sizes may have reduced power to detect true differences; nevertheless, this study provides support that greater standing innate immunity in high altitude animals may reflect greater investment into constitutive defense.

First multicenter coprological survey on helminth parasite communities of free-living loggerhead sea turtles Caretta caretta (Linnaeus, 1758) from the Adriatic Sea and Northern Ionian Sea

The prevalence of endoparasite infections in 83 free-living specimens of Caretta caretta, classified as vulnerable species, from the Adriatic Sea and Northern Ionian Sea was investigated by coprological examination. Thirty-seven (44.6%) turtles were found to be infected with helminths. The helminth infections found were: Rhytidodes gelatinosus and Sulcascaris sulcata (18.1% each), Hapalotrema mistroides (13.2%), Cymatocarpus solearis (9.6%), Eniodotrema megachondrus (7.2%), Kathlania/Tonaudia sp. (3.6%), Neospirorchis sp., Octangium sagitta and Plesiochorus cymbiformis (1.2% each). There were no significant differences in the total prevalence of helminth infections between sexes, size classes, and seasonal periods. Conversely, the prevalence of helminth infections was significantly higher (P < 0.01) in accidentally caught turtles than in stranded turtles. Highly significant differences in prevalence of helminthiases were also seen among marine sampling areas. This report provides important baseline information about the helminth fauna of free-living C. caretta in the examined geographical region. This is also the first report of O. sagitta infection in C. caretta thus broadening the host range of the parasite.

Parasites in feces of the endemic rattlesnake, Crotalus triseriatus (Serpentes: Viperidae), from Mexican highlands

There are few studies about parasitic infections in Crotalus triseriatus (Wagler, 1830), an endemic rattlesnake from the highlands of central Mexico. This species occupies several habitats, from conserved forested regions to heavily impacted landscapes. To increase the parasitological knowledge of this reptile species without impacting populations, we obtained fecal samples of 16 rattlesnakes between 2012 and 2014 from Toluca Valley, Mexico. By using flotation technique, we found oocysts of Eimeria sp. and eggs of Capillariidae sp. The most frequent parasite was Eimeria sp. (62.5%). This study provides the first records of occurrence of parasites in reptilian feces from Mexico. Our results may be important for wildlife conservation purposes, for example, they could indicate of the population health of this species during processes of translocation.

Characterization of ecto- and endoparasite communities of wild Mediterranean teleosts by a metabarcoding approach

Next-generation sequencing methods are increasingly used to identify eukaryotic, unicellular and multicellular symbiont communities within hosts. In this study, we analyzed the non-specific reads obtained during a metabarcoding survey of the bacterial communities associated to three different tissues collected from 13 wild Mediterranean teleost fish species. In total, 30 eukaryotic genera were identified as putative parasites of teleosts, associated to skin mucus, gills mucus and intestine: 2 ascomycetes, 4 arthropods, 2 cnidarians, 7 nematodes, 10 platyhelminthes, 4 apicomplexans, 1 ciliate as well as one order in dinoflagellates (Syndiniales). These results highlighted that (1) the metabarcoding approach was able to uncover a large spectrum of symbiotic organisms associated to the fish species studied, (2) symbionts not yet identified in several teleost species were putatively present, (3) the parasitic diversity differed markedly across host species and (4) in most cases, the distribution of known parasitic genera within tissues is in accordance with the literature. The current work illustrates the large insights that can be gained by making maximum use of data from a metabarcoding approach.

Opportunities and challenges in metabarcoding approaches for helminth community identification in wild mammals

Despite metabarcoding being widely used to analyse bacterial community composition, its application in parasitological research remains limited. What interest there has been has focused on previously intractable research settings where traditional methods are inappropriate, for example, in longitudinal studies and studies involving endangered species. In settings such as these, non-invasive sampling combined with metabarcoding can provide a fast and accurate assessment of component communities. In this paper we review the use of metabarcoding in the study of helminth communities in wild mammals, outlining the necessary procedures from sample collection to statistical analysis. We highlight the limitations of the metabarcoding approach and speculate on what type of parasitological study would benefit from such methods in the future.

The diversity and evolution of nematodes (Pharyngodonidae) infecting New Zealand lizards

Host-parasite co-evolutionary studies can shed light on diversity and the processes that shape it. Molecular methods have proven to be an indispensable tool in this task, often uncovering unseen diversity. This study used two nuclear markers (18S rRNA and 28S rRNA) and one mitochondrial (cytochrome oxidase subunit I) marker to investigate the diversity of nematodes of the family Pharyngodonidae parasitizing New Zealand (NZ) lizards (lygosomine skinks and diplodactylid geckos) and to explore their co-evolutionary history. A Bayesian approach was used to infer phylogenetic relationships of the parasitic nematodes. Analyses revealed that nematodes parasitizing skinks, currently classified as Skrjabinodon, are more closely related to Spauligodon than to Skrjabinodon infecting NZ geckos. Genetic analyses also uncovered previously undetected diversity within NZ gecko nematodes and provided evidence for several provisionally cryptic species. We also examined the level of host-parasite phylogenetic congruence using a global-fit approach. Significant congruence was detected between gecko-Skrjabinodon phylogenies, but our results indicated that strict co-speciation is not the main co-evolutionary process shaping the associations between NZ skinks and geckos and their parasitic nematodes. However, further sampling is required to fully resolve co-phylogenetic patterns of diversification in this host-parasite system.

The intestinal helminth community of the spiny-tailed lizard Darevskia rudis (Squamata, Lacertidae) from northern Turkey

Populations of the lizard Darevskia rudis (Bedriaga, 1886) from northern Anatolia were examined for intestinal parasites in adult specimens. One cestode, Nematotaenia tarentolae López-Neyra, 1944 and four nematode species, Spauligodon saxicolae Sharpilo, 1962, Skrjabinelazia hoffmanni Li, 1934, Oswaldocruzia filiformis (Goeze, 1782) and Strongyloides darevskyi Sharpilo, 1976, were found. Three of these nematodes, S. saxicolae, S. hoffmanni and S. darevskyi are suggested to be part of a module in the network of Darevskia spp. and their parasites. Only one, S. darevskyi, was identified as a Darevskia spp. specialist. The very low infection and diversity parameters are indicative of the depauperate helminth communities found in this lacertid lizard, falling among the lowest within the Palaearctic saurians. Nevertheless these values are higher than those found in parthenogenetic Darevskia spp. Interpopulation variation in the intensity of S. saxicolae and N. tarentolae is attributable to local changes in ecological conditions. On the other hand, parasite abundance and richness increased in the warmer localities, while the effect of lizard sex and size on infection was negligible. The structure of these helminth communities in D. rudis are compared with those observed in other European lacertid lizards.

A combined parasitological molecular approach for noninvasive characterization of parasitic nematode communities in wild hosts

Most hosts are concurrently or sequentially infected with multiple parasites; thus, fully understanding interactions between individual parasite species and their hosts depends on accurate characterization of the parasite community. For parasitic nematodes, noninvasive methods for obtaining quantitative, species-specific infection data in wildlife are often unreliable. Consequently, characterization of gastrointestinal nematode communities of wild hosts has largely relied on lethal sampling to isolate and enumerate adult worms directly from the tissues of dead hosts. The necessity of lethal sampling severely restricts the host species that can be studied, the adequacy of sample sizes to assess diversity, the geographic scope of collections and the research questions that can be addressed. Focusing on gastrointestinal nematodes of wild African buffalo, we evaluated whether accurate characterization of nematode communities could be made using a noninvasive technique that combined conventional parasitological approaches with molecular barcoding. To establish the reliability of this new method, we compared estimates of gastrointestinal nematode abundance, prevalence, richness and community composition derived from lethal sampling with estimates derived from our noninvasive approach. Our noninvasive technique accurately estimated total and species-specific worm abundances, as well as worm prevalence and community composition when compared to the lethal sampling method. Importantly, the rate of parasite species discovery was similar for both methods, and only a modest number of barcoded larvae (n = 10) were needed to capture key aspects of parasite community composition. Overall, this new noninvasive strategy offers numerous advantages over lethal sampling methods for studying nematode-host interactions in wildlife and can readily be applied to a range of study systems.